You push the "D" the tab in and pull it back one click at a time. between each time you pull it back, re-check over and over for full swing on the throttle. When you get it close and there is no slack left in the cable, you may end up with a choice between two "click" positions and you may be undecided on which one to use.
The first option will be only full tension on the cable with zero slack.
Like the first, the second option will also be full tension on the cable. But this time you will see that the cable mounting tab will very, very slightly be tweaked with the pull.
This second option is usually as tight as it gets before jerking the cable housing forward. And this is the way I used to like mine when I had a 200.